The present invention is related to an auxiliary-bicycle torsion sensing and large gear plate minimization apparatus, especially to an apparatus arranged at the transmission apparatus of auto-auxiliary-bicycle for sensing the torsion and acceleration of stepping force as rider is riding the auto-auxiliary-bicycle. Hence the large gear is minimized and the variation of outlook beautification is met.
In current market, the wheels of popular auto-bicycle (also called auto-auxiliary-bicycle) are driven to rotate mainly by arranging auxiliary devices at bicycle (auxiliary-bicycle), such as battery, driving motor, and transmission apparatus, etc. When rider steps on the treadles of bicycle, besides the stepping force drives the wheels, the driven motor also generates a power that is transmitted by transmission apparatus and drives bicycle""s wheels to rotate. Hence the strength of the rider to drive the bicycle may be reduced and the object of auxiliary-bicycle is met.
Because the rider needs different powers output from driven motor to drive the wheels according to the uphill and downhill situations and to different driving speeds, each manufacturer also develops stepping force sensor for detecting the stepping strength of bicycle rider. And according to the stepping force detected by the sensor, the power transmitted by the driven motor is controlled. In general, the current prior stepping force sensing manners includes following three methods: transferring torsion value into axial displacement, absolute angular displacement and relative angular displacement. Wherein the method of relative angular displacement, during low driving speed, may not obtain a continuous signal and therefore is scarcely adapted. As for axial displacement and absolute angular displacement, their sensing methods possess no such problem.
Also the large gear plate of traditional bicycle is too large, during covering transmission chain, covering volume is too big and outlook is disgraceful. If the size of traditional large gear plate is reduced, it can meet the object of outlook beautification.
As shown in FIG. 1, wherein one example for the patent of U.S. Pat. No. 5,474,148 adapts the torsion sensing apparatus of absolute angular displacement. The major mechanisms of this torsion sensing apparatus are: stepping force directly drives the unidirectional device 42 by crank axle 28, the power is transmitted to the planet arm 44 of a planet gear set by unidirectional device 42, and finally power is output by the ring gear 46 connected with large gear plate of bicycle, wherein the sun gear is connected to sensor. For a planet gear system, at the situation of uniform speed, since larger the stepping force is, larger the torsion input to planet arm 44 is, so when sun gear 45 is connected to an elastic body, i.e. the torsion value of sun gear 45 may be transferred into the absolute angular displacement of elastic body. Since the absolute angular displacement is proportional to stepping force, so it may control the power output of driving motor. However, since this prior art needs use of many sets of complicated parts of planet gears and umbrella gears, etc, so not only the structure is complicated, but also the costs of parts manufacture and assembly are relatively higher. Additionally, since the driving motor of U.S. Pat. No. 5,474,148 outputs the power to large gear plate to drive wheels through ring gear 46, so driving motor also influences the torsion value of sun gear 45 as power is output. Namely, if the influence of stepping force of rider on torsion value of sun gear is firstly overcome over (or larger than) that of driving motor, then the driving motor will continue to output power. So the power output of prior art is slower, and can not respond instantly to the rider""s power requirement. Additionally, in prior art, since the planet arm 44 is used to transmit power to wheels by rotating the ring gear 46, so the reducing speed of this device is larger, and U.S. Pat. No. 5,474,148 also applies such device to proceed the task of reducing speed of rotation speed of driving motor. However, when the rider does not use the driving motor to output power (i.e. battery is out of power), the rider will step more rounds to make the crank axle 28 drive the wheel to move and it causes lots of inconveniences.
There is another prior art example for applying absolute angular displacement method as torsion sensing apparatus. The power transmission of driving motor and stepping force sensing are proceeded mainly by the connection transmission of multi-sets of differential umbrella gear set. Besides its shortcoming is the cost increase caused by the application of multi-sets of differential umbrella gear set, its main shortcoming is focused on the crank axle that is directly connected and actuated with the large gear plate by the unidirectional umbrella gear ratchet. So, when the driving motor can not output power, the crank axle and the large gear plate rotate synchronously with one to one speed ratio. This sort of application lacks flexibility.
Another prior art example is to apply the axle direction displacement method as torsion sensing apparatus. Its torsion sensing method is mainly comprised by stepping force to drive a screw through crank axle. As the screw is rotating, it will cause a displacement along nut axle direction for the screw and also press down the spring located between screw and nut. Finally the nut outputs the power to gear plate through unidirectional device. Therefore by the magnitude of elastic coefficient of spring, the ratio between the value of stepping force and axle direction displacement of screw can be determined. So the stepping force value can be known just by sensor to measure the magnitude of axle direction displacement of screw. The shortcoming of this prior art is that the match between screw and nut is easily interfered by the external objects or fragment generated by the operation of parts of itself. They may further be jammed seriously between screw and nut to make the stepping force sensing become inaccurate. Furthermore, when there is no power output from the driving motor, the crank axle and gear plate of patent of U.S. Pat. No. 288,427 could only synchronously rotate with one to one speed ratio and that is of less flexibility in real application.
Another kind of prior art example is applying axle direction displacement method as torsion sensing apparatus. Its torsion sensing method is mainly by stepping force to drive a torsion rod through crank axle. Because the skew planes structure among the torsion rods, it causes an axle direction displacement for the torsion rod. This displacement is further magnified from rod to rod. Therefore, the value of stepping force is known by measuring the magnified axle direction displacement of lever. The shortcomings of this prior art are that besides the structure is more complicated and the cost is higher, also the sensing accuracy is easily interfered by the fragment generated by the above-mentioned parts of itself and crank axle and gear plate can only synchronously rotate with one to one speed ratio.
The main object of the present invention is to provide an auxiliary-bicycle torsion sensing and large gear plate minimization apparatus, which has the merits of simple structure, lower manufacture cost, accurate stepping force sensing for rider, less interference by parts fragment, and design flexibility enhanced by application of different rotation speed between the crank axle stepped by rider and the large gear plate. These merits will overcome the shortcomings of prior arts. And the minimization of large gear plate may promote the outlook beautification of auxiliary-bicycle.
Another object of the present invention is to provide an auxiliary-bicycle torsion sensing apparatus, wherein the torsion of stepping force of rider is transmitted by the swing arm of planet gear system and the absolute angular displacement of swing arm is measured by a sensing apparatus to further control the driving apparatus to output power to drive the wheels to rotate. This arrangement has the advantages of simple structure, low manufacture cost, accurate stepping force measurement, and instant accurate responding rider""s stepping force magnitude from the power output of driving apparatus, etc. And the minimization of large gear plate for auxiliary-bicycle may meet the object of outlook beautification.
To achieve above-mentioned objects, an auxiliary-bicycle torsion sensing apparatus of the present invention at least includes a sun gear, a unidirectional device, a planet gear set, a second planet gear, and a sensing apparatus. The auxiliary-bicycle torsion sensing apparatus is provided for arranging at transmission apparatus of auxiliary-bicycle. The transmission apparatus at least includes a crank axle, a gear plate and speed-variation gear set. The power output of a driving apparatus may be controlled by the rotation of crank axle. The power output of driving apparatus can drive gear plate to rotate through the transmission of transmission apparatus.
The sun gear of the auxiliary-bicycle torsion sensing apparatus is fixed on the crank axle and driven to rotate with the crank axle. The planet gear set at least includes a swing arm and a first planet gear. The swing gear is pivotally arranged on the crank axle by pivotal rotation method. The first gear is pivotally arranged on the swing arm and driven to rotate together with the sun gear. The first planet gear may be driven to rotate by the rotation of crank gear. And the swing arm further generates a rotation torsion of upward rotation which is same as that of the sun gear. The sensing apparatus is connected to one side of the swing arm, which can measure the rotation torsion of the swing arm and generates a sensing signal to control the power output of the driving apparatus. The unidirectional device is connected to the gear plate and can proceed single direction transmission. The second planet gear is arranged on the planet gear set and driven together with the first planet gear. The second gear is driven together with the unidirectional device. And the single transmission direction of unidirectional device can make the second planet gear drive gear plate to rotate, but gear plate can not drive the second planet gear to rotate.
In a preferable embodiment, the auxiliary-bicycle torsion sensing apparatus further includes a medium gear and a ring gear. The medium gear matches with the second gear and the ring gear matches with both medium gear and unidirectional device. And the sensing apparatus includes a pushing pillar, a replacement element, a pushing block, and a stress sensor. One end of the pushing pillar pushes against the swing arm. Another end is connected with the stress sensor. The pushing pillar may transfer the rotation torsion of the swing arm to stress sensor. The pushing block is pushing against the swing arm. The replacement element is connected to the pushing pillar. An elastic force may be provided to make the pushing pillar maintain a predetermined position under the state of no external force.
Preferable, the speed-variation gear set is comprised of several matching multi-level gears.
Preferable, the driving apparatus is a electric driving motor.
For your esteem review committee member to further understand and recognize the present invention, in accordance with several drawings a detailed description is presented as following.